Electric lamp and discharge devices – Spark plugs – Particular electrode structure or spacing
Reexamination Certificate
1998-09-25
2001-03-06
Day, Michael H. (Department: 2879)
Electric lamp and discharge devices
Spark plugs
Particular electrode structure or spacing
C313S143000, C313S118000
Reexamination Certificate
active
06198209
ABSTRACT:
TECHNICAL FIELD
This invention relates to a spark plug and more particularly to a collar shielding a gap between an electrode and conductor of the spark plug.
BACKGROUND ART
Spark plugs used to ignite gaseous fuel in the combustion chambers of internal combustion engines typically have a gap between the electrode and conductor at one end portion of the spark plug. Such spark plugs are often referred to as “J-gap” type spark plugs. In rich gaseous fuel environments, these spark plugs have proven to be adequate to cause ignition of the fuel and satisfactory engine operation.
Tighter government emission regulations have prompted changes in internal combustion engine designs and operating parameters. In gaseous fueled engines, cleaner burning has been achieved by running the engine on leaner air to gaseous fuel ratio mixtures. Cleaner burning of leaner air to gaseous fuel mixtures after initial combustion has been further enhanced by adding swirl to the combustion chambers inlet air charge. This Swirl, however, induces turbulence near the gap of the “J-gap” spark plug and inhibits initial ignition of the gaseous fuel to air ratio mixture.
It has been known to provide an adapter for a “J-gap ” spark plug. An example of such a spark plug is shown in U.S. Pat. No. 4,182,281, to Leo A. Heintzelman, dated Jan. 8, 1980. The adapter is screw threadably connected to the threaded end portion of the spark plug and encloses the open end portion of the spark plug. Such adapters tend to be expensive to manufacture and do not adequately provide the desired ignition characteristics.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the present invention, a shielded spark plug assembly is provided. The spark plug assembly has a housing. The housing has an end, an axis, and a bore opening at the end. An electrode having an end is disposed in the bore. The electrode extends axially relative to the bore. The end of the electrode is located a predetermined axial distance “b” from the housing end. A conducting member is connected to the end of the housing and extends radially relative to the bore of the housing to a location adjacent to and spaced a predetermined gap distance from the electrode end. A collar has first and second spaced apart ends and a bore opening at the first and second ends of said collar. The collar first end is connected to the end of the housing and the collar second end is located a predetermined axial distance “a” spaced from the housing end. The conducting member is located between the end of the housing and the second end of the collar. The collar shields the electrode and the conducting member.
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Baldwin Darryl D.
Brandes David W.
Staab Richard P.
Caterpillar Inc.
Day Michael H.
Hickman Alan J.
Williams Joseph
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